One-point mooring buoy for loading or unloading ships

ABSTRACT

Single buoy mooring for (un)loading tankers comprising a floating body anchored to the seabottom, a ring arranged on top of the body in such a way that it is rotatable around a vertical axis relative to the body and mooring cables or chains secured to the ring tangentially.

United States Patent Rutten et al.

ONE-POINT MOORING BUOY FOR LOADING OR UNLOADING SHIPS Inventors: l-lendrlkus S. Rutten, Voorburg; Gerard Krulsman, Reeuwijk; Johan DeGroot; Slmon Weatra; Abraham P. Bavelaar, The Hague. all of Netherlands Assignee: Shell Oll Company, New York, NY.

Filed: Dec. 5, 1969 Appl. No.: 882,800

Foreign Application Priority Data Dec. 20, 1968 Netherlands....; ..6818357 U.S. Cl ..9/8 P Int. Cl ..B63b 21/00 Field of Search ..9/8 P, 8 R; 114/230 [4 1 Mar. 28, 1972 [56] Reierences Cited UNITED STATES PATENTS 3,178,737 4/l965 Bracky ..9/8 P 3,236,267 2/l966 Bily ....9/8 P 3,414,918 l2/l968 Petrie et al. ....9/8 P 3,465,374 9/1969 Johnson et al ....9/8 P FOREIGN PATENTS OR APPLICATIONS 977,272 12/ 1964 Great Britain ..9/8

Primary Examiner-Milton Buchler Assistant Examiner-Gregory W. OConnor Attorney-Preling E. Baker and J. H. McCarthy ABSTRACT Single buoy mooring for (un)loading tankers comprising a floating body anchored to the seabottom, a ring arranged on top of the body in such a way that it is rotatable around a vertical axis relative to the body and mooring cables or chains secured to the ring tangentially.

3 Claims, 8 Drawing Figures Patented Mach 28, 1972 3,651,525

8 Sheets-Sheet 1 INVENTORS:

HENDRIKUS S. RUTTEN GERARD KRUISMAN JOHAN DE GROOT SIMON WESTRA ABRAHAM P. BAVELAAR BY:

THEIR ATTORNEY Patented March 28, 1972 3,651,525

8 Sheets-Sheet 2 INVENTORS:

HENDRIKUS sf RUTTEN GERARD KRUISMAN JOHAN DE GROOT SIMON WESTRA ABRAHAM P. BAVELAAR THEIR TTORNEY Patented March 28, 1972 3,651,525

8 Sheets-Sheet 5 INVENTORSI HENDRIKUS -S. RUTTEN GERARD KRUISMAN JOHAN DE GROOT SIMON WESTRA ABR HAM P. BAVELAAR THEIR ATTORNEY Patented arch 28, 1972 8 Sheets-Sheet 4 INVENTORS:

HENDRIKUS S. RUTTEN GERARD KR MAN JOHAN DE G OT SIMON WESTRA ABR HAM P. BAVELAAR BY: 4 THEIR/A TTORNEY Patented March 28, 1972 3,651,525

8 Sheets-Sheet 5 O O 106 105 106 108 106 105 106 108 105 105 106105 0 o 'FIG.5

THEIR ATTORNEY Patented March 28, 1972 3,651,525

8 Sheets-Sheet 6 FIG.6

INVENTORSZ v HENDRIKUS S. RUTTEN GERARD KRUISMAN JOHAN DE GROOT SIMON WESTRA ABRAHAM P. BAVELAAR THEIR ATTORNEY R A M A T L T N E Y M A R N 6 M A B R R P Z T SK T E A U D M) m m D W R R R N H m ODAAWA E T N R H M H N E E O l B T WHGJSA: Y m B Patented March 28, 1972 8 Sheets-Sheet 8 I FIG.8

INVENTORS:

HENDRIKUS S. RUTTEN GERARD KRUISMAN JOHAN DE GROOT SIMON WESTRA ABRAHAM P. BAVELAAR ea Z THEIR Z TORNEY ONE-POINT MOORING BUOY FOR LOADING OR UNLOADING SHIPS BACKGROUND OF THE INVENTION The invention relates to a one-point mooring buoy for loading or unloading a gas or liquid to or from a ship, pertains more particularly to a buoy body provided with a rotatable part to which a ship can be fastened by means of a mooring cable or mooring chain.

Buoys of this type, which are especially important for offshore loading or unloading oil or gas tankers, have been increasingly used in recent years. Buoys of this type are described, inter alia, in Applicants U.S. Pat. Nos. 3,187,355 and 3,264,662. The ever-increasing use of very large tankers has resulted in an ever-growing need for such one-point mooring buoys, since the heavy draught of very large tankers prevents them from entering many existing port, so that offshore loading or unloading is often the only alternative.

Since very large tankers often have a capacity up to 300,000 tons and more, it is desirable that a one-point mooring buoy should be available which is suitable for mooring and loading and unloading very large tankers.

SUMMARY OF THE INVENTION Accordingly, the invention relates to a one-point mooring buoy which transmits the forces of the mooring cables or mooring chains of the ship as favorably as possible to the buoy, so that the latter is particularly, although not exclusively, suitable for use with very large tankers.

To this end the one-point mooring buoy according to the invention is characterized in that the rotatable part is designed as a ring, which ring is journaled on the upper part of the buoy body, in such a way that the ring can rotate around a vertical axis, the mooring cable or mooring chain engaging the ring tangentially.

In an attractive embodiment of the buoy according to the invention the end of the mooring cable or mooringchain situated near the buoy is split up into two parts, each of which engaging the ring tangentially.

The ring may advantageously be journaled on the buoy body by means of a roller bearing which is so designed that it can absorb both large axial and large radial forces.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be illustrated with reference to the Figures, which show an embodiment of the invention in which:

FIG. 1 is a vertical cross section of the upper part of the buoy according to the invention;

FIG. 2 is a top plan view of the buoy of FIG. 1;

FIG. 3 is a side view of the buoy;

FIG. 4 is an enlarged cross section of the bearing;

FIG. 5 is a schematic top plan view of the buoy with the hoses connecting the buoy with the submarine pipeline;

FIG. 6 is a schematic side view of the buoy with the hoses connecting the buoy with the submarine pipeline;

FIG. 7 is a top plan view of a float as used for the hoses shown in FIGS. 5 and 6;

FIG. 8 is a cross section [-1 of the float shown in FIG. 7.

A buoy body consists of a cylindrical inner wall 6, a cylindrical outer wall 5, a deck 7, a bottom wall 13,- radial frames 3 and radial partitions 4. A collar 8 is fitted to the lower part of the outer wall 5. The collar 8 is designed to be fastened to anchor cables or anchor chains to enable the buoy to be anchored. To this end the collar 8 is provided with openings 10 to which the leading ends of the anchor chains or anchor cables can be fastened. The chain-dotted lines 9 in FIG. 3 shown diagrammatically the manner in which the anchor chains or anchor cables normally run. The upper part of the outer wall 5 is provided with a fender 11, for example, made of rubber. The buoy body 1 is of such a watertight construction that it has always buoyancy. If desired, the interior of the buoy body 1 may be filled with foam plastic, for example, polyurethane foam, so that the buoy body retains its buoyancy even in case of damage, for example, by a collision.

The center of the buoy body 1 accommodates a rotatable pipe coupling 12. This pipe coupling 12 consists of a lower part 16 which is fixedly secured to the buoy body 1, a head 15 being so mounted on the lower part 16 by means of a bearing that the head 15 can rotate around a vertical axis relative to the lower part 16. A sealing ring 18 ensures that the rotatable coupling between the lower part 16 and the head 15 is liquidtight.

Two radial pipe lengths 19 are connected to the head 15. Each of the pipe lengths 19 is connected to a bend 21 by means of a flexible intermediate piece 20. Each bend 21 is in turn connected to a line section 24 by way of a valve 23. To

the end of each line section 24 a bend 26 is secured by means the top of which is sealed, inter alia, by a sealing member 33,

which bearing 32 supports a heavy annular part or member 28 in such a way that the annular part 28 can rotate around a vertical shaft relative to the buoy body 1.

A radially extending element 29 is fixedly secured to the annular part 28. The line sections 24 are attached to this element 29 by means of fastening elements 30 and 31. Each of the bends 21 is fitted to the annular part 28 by means of fastening elements 36.

The head 15 is provided with a light 35 as a warning against collision to navigation.

The lower part 16 of the pipe coupling 12 is provided with two radial pipe lengths 37. Each of these pipe lengths 37 can be connected to a pipeline on the bottom of the water (its surface is indicated by the reference numeral 2) for the supply or discharge of gas or liquid.

Diametrically opposite to the element 29 a radially extending platform 38 is fixedly secured to the annular part 28. This platform 38 is so designed that it can take up a quantity of ballast (not shown). The platform 38 is provided with a small hoist 39 of a construction known per se. Further, a ladder 40 is attached to the platform 38 to enable the crew to climb on the platform 38 from the deck 7. A protective structure 41 is fitted on the platform 38 and the ring 28.

The annular part 28 is also provided with a farther extending platform which is indicated by the reference numeral 45. A platform 46 is secured to the annular part 28 diametrically opposite to the platform 45. This platform 46 is equipped with a winch 47 and with a ladder 48.

Above the platform 45 and two chains 49 and 50 (the manner in which they run is partly indicated by a chain-dotted line) are tangentially secured to the annular part 28 by means of U-shaped connecting pieces 51 with associated pins 52. The pins 52 are secured horizontally to the annular part 28, in such a way that the chains 49 and 50 can swing in a vertical plane. The free ends of the chains 49 and 50 are connected to each other by means of a ring 53. A mooring line of chain 54 (its course is also partly indicated by a chain-dotted line) is attached to the other side of the ring 53. The chain 54, which will hereinafter be referred to as mooring chain, serves to moor a ship to the buoy, for example, by two nylon mooring hawsers. In FIG. 1 the chain-dotted line inclining vertically downwards shows the course of the mooring chain 54 when no ship is moored to the buoy. In this case the mooring chain 54 is vertically suspended. The chain-dotted lines 54a and 54b show some other positions of the mooring chain 54 and of the chains 49 and 50, respectively, for example, when the ship moored to the buoy is loaded to a greater or lesser extent. A steel structure 58 is fitted on the platform 45 and partly to the ring 28. The steel structure 58 serves to guide the mooring chain 54, especially in the event of the ship floating past the buoy owing to certain current and wind conditions.

The platform 38, 46 and the ring 28 are provided with a railing 59. The buoy body 1 is provided with a number of manholes 60 and 61, respectively, if desired equipped with associated covers, which holes are accessible by means of ladders 62 and 63, respectively. The end of the radially extending element 29 is provided with a ladder 64.

Cable sheaves 70 and 71 act as guides for cables 72, which serve to fasten the floating hoses (not shown) to the bends 26. The cables 72 can be attached to an eye 73 on the radially extending element 29.

The platform 38 is provided with a vertical guide pin 74. This pin serves to prevent mooring hawsers from getting under the extending part 38 when the ship is floating past the buoy.

In order to permit adjustment of the rotational resistance of the ring 28 as required a mechanism is provided, of which a possible embodiment is diagrammatically shown in FIG. 3. This mechanism consists of a bar 75 attached to the ring 28, the end of which bar is provided with a sliding shoe 76. The resistance encountered by the ring 28 during rotation can be adjusted by shifting the sliding shoe 76 upwards or downwards. It is even possible to lock the ring 28 by means of this mechanism.

It will be obvious that it is possible to use alternative embodiments of the mechanism for adjusting the rotational resistance of the ring 28, and for locking it. For example, the ring 28 may be provided with a clamp, the jaw of which engages a fixed rail arranged concentrically with the ring 28.

When the ship, for example, a tanker is fastened to the mooring chain 54, in such a way that the bow of the ship is attached to the free end, the ship will be capable of shifting its position in such a way that it offers a minimum resistance to the wind, current and wave forces, as is usually the case with one-point mooring buoys. Since the ring 28 is rotatably fastened to the buoy body 1, the ship can freely swing around the one-point mooring buoy. Owing to the provision of the bearing 32 the ring 28 can rotate around a vertical axis without difficulty. The bearing 32 is designed as a roller bearmg.

This roller bearing 32 is so designed that it can absorb both horizontal and vertical forces. Moreover, the roller bearing is so robustly constructed that it is adapted to take up very large forces. This is necessary, since the roller bearing 32 must be capable of absorbing the forces caused by the fact that a ship is moored with its bow to the ring 28 by means of the chain 54. It will be obvious that the roller bearing 32 must be able to take up both vertical and horizontal mooring forces. FIG. 1 shows that the mooring chain 54 can form different angles with the horizontal plane; in this connection see the chaindotted lines 54a and 541:. Thus, the horizontal and the vertical forces exerted on the ring 28 will vary with the angle with the horizontal plane.

The roller bearing 32, which must be able to absorb all the mooring forces, must therefore meet stringent requirements. This roller hearing, which may have an inner diameter of about 13 feet or more, is shown in detail in FIG. 4 and will be discussed below.

The upper part of the cylindrical inner wall 6 is of an exceptionally robust design so as to be able to transmit the forces ex erted on the bearing 32 to the buoy body 1. This upper part extends above the deck 7 and is provided on the outside with a flat ring 80, which is fixedly secured, for example, by welding to the part of the wall 6 extending above the deck 7. The ring 80 supports the inner ring 81 of the roller bearing 32, as shown. A plasticpaste or cement 86 may advantageously be applied between the inner ring 81, the ring 80 and the wall 6. A bolt 82 serves to fix the inner ring 81 securely. The roller bearing 32 is provided with two outer rings, namely a lower outer ring 83 and an upper outer ring 84. These rings 83 and 84 are connected to the annular part 28 in the way described below.

A flat ring 85 is fixedly secured to the annular part 28, for example, by welding. By means of a bolt and nut connection 87 the outer rings 83 and 84 are fixedly secured to the ring 85. A plastic paste or cement 88 is also applied between the outer ring 84 and the annular part 28. Horizontal rollers 89 and vertical rollers 90 are provided between the inner and outer rings 81, 83 and 84. The horizontal rollers 89 serve to absorb the vertical forces and the vertical rollers 90 serve to take up the horizontal forces. Sealing rings 91, 92 and 93 between the outer and inner rings prevent the ingress of dirt. Additional protection against the ingress of sea water is provided by the sealing ring 94 at the bottom and the labyrinth seal 95 at the top. Penetrating sea water can be drained from the seal 95 through a tube 96. Eyes 27 are fitted to the annular part 28 for hoisting purposes and for fastening guy lines or the like.

Submarine pipelines 101 (see FIG. 6) serve to supply or discharge liquid or gas to or from the buoy. The pipelines 101 extend along the sea bottom 102. Since the buoy 1 is constantly moving on the water, the connection between the metal pipelines 101 with the buoy 1 must be flexible. A flexible connection between the pipelines 101 and the buoy 1 can simply be ensured by means of hoses 103, which are kept in an S-bend lying in a vertical plane, by means of floats 104. The hoses 103 are built up from sections 105, which are connected to each other by means of flanges 106.

FIG. 5 shows the case where two hoses 103 are used, but it is, of course, also possible to use only one hose 103 or more than two hoses 103.

The floats 104 are shown in detail in the FIGS. 7 and 8 and will now be discussed.

Each of two parallel metal pipes 107, the ends of which are provided with flanges 108, is enclosed by coaxial hollow cylinders 109, which cylinders are connected to the metal pipes 107 by means of and plates and radial partitions 111, the arrangement being such that two chambers 1 13 and 114, respectively, are formed inside each cylinder 109. The two cylinders shown are fixedly connected to each other by means of plates 1 12.

A pair of lines 115 is connected to the ends of each chamber 1 14. The free end ofeach line 115 is provided with a valve 116 and a coupling member 117 for connecting a supply or a discharge line to the line 115. The chambers 1 14 are each provided with a filling plug 118, while the chambers 113 may each be provided with a vent valve 1 19.

As is shown in FIGS. 5 and 6, each of the floats 104 is fitted between a pair of hose sections 105 by connecting the flanges 106 to the flanges 108. Thus, the hose sections 105 are directly connected up with the metal pipes 107, so that the liquid or the gas can flow through the pipes 107 during loading or unloading.

The hoses 103 are mounted as follows.

The hose sections 105 are connected to each other by means of the flanges 106, the floats 104 being inserted between some pairs of sections 105, for example, as shown in the FIGS. 5 and 6, in such a way that the hoses 103 of the required lengths are obtained.

The ends of the resultant hoses 103 are now connected to the line 101 and the buoy 1, respectively. To accomplish this, it is necessary for the buoyancy of the floats 104 to be reduced to nil by filling the floats 104 with a suitable liquid.

After the hoses 103 have been mounted in the way described above, the buoyancy of the floats 104 must be adjusted in such a way that the hoses 103 adopt the S-shape shown in FIG. 6.

The procedure is as follows. Part of the ballast liquid present in the chambers 114 is discharged until the floats 104 have obtained the buoyancy required. This may be effected by connecting a compressed air line (not shown) to the lines 115 on one side of each float 104. Subsequently, the relevant valves 116 are opened and compressed air is passed to the chambers 114. Once, a sufiiciently high pressure has been built up the opposite valve 1 16 is opened, so that ballast liquid is forced out of the chambers 114. Once the float 104 has reached the desired level above the sea bottom 102, the latter valve 116 is again closed, so that no further ballast liquid can flow from the chambers 114. The air hose is then disconnected from the float.

We claim as our invention:

l. A one-point mooring buoy for mooring a floating vessel and communicating fluids therebetween, said buoy comprisa floating body having a portion thereof adapted to extend above the surface of a body of water when floating therein;

an annular member for supporting attachment means for a mooring line;

said annular member being journaled about a vertical axis on said floating body above the surface of said body of water; attaching means tangentially secured to said annular member for attaching and supporting a mooring line; 

1. A one-point mooring buoy for mooring a floating vessel and communicating fluids therebetween, said buoy comprising: a floating body having a portion thereof adapted to extend above the surface of a body of water when floating therein; an annular member for supporting attachment means for a mooring line; said annular member being journaled about a vertical axis on said floating body above the surface of said body of water; attaching means tangentially secured to said annular member for attaching and supporting a mooring line; a submarine pipeline; and a flexible conduit communicating with said pipeline and a conduit carried by said buoy; said flexible member being maintained in a vertically disposed S-bend by means of adjustable floats.
 2. The buoy of claim 1, wherein said floats comprise chambers; and; means for transferring liquid to and from said chambers.
 3. The buoy of claim 2, including a plurality of flexible conduits and means to maintain said conduits in parallel relationship. 